This invention relates generally to the field of dispenser devices used to introduce small quantities of a chemical solution into a flowing liquid, the chemical solution being created by dissolving a solid or granular chemical. More particularly, the invention relates to such devices to be used as a component in assemblies of the type commonly found in liquid circulation or supply systems, such as water supply systems, where the rate of introduction of the dissolved chemical into the water is proportional to the flow volume of the water stream to insure proper concentration percentage.
It is desirable or necessary in many water supply or recirculation systems, such as water for household or industrial use, or water for use in spas and pools, to add certain chemicals to the water to control bacteria or fungal growth, corrosion, scale deposits, etc. Commonly known additives include chlorine, polyphosphate or sodium silicate. Such additives are typically supplied in solid or granular form for ease of handling, and must therefore be dissolved in liquid and introduced into the water flow. It is imperative that the chemical additives be supplied in the proper concentration, and it is important that the mechanism for adding the chemical solutions provide for proper rate introduction with little variation in concentration. Many conventional systems fail these criteria, the mechanisms being unable to prevent variations in concentration and introduction rates, especially in circumstances where the water flow is not continuous and varies in pressure
The most simplistic solid chemical additive mechanisms simply divert all or a portion of the water flow stream through a container holding the solid chemical. The water flowing from the container will then include an amount of dissolved chemical. These devices suffer from lack of dispensing control, since the amount of chemical present in the outflow is dependent on the volume of solid chemical in the container. As that volume decreases, the concentration of dissolved chemical in the outflow also decreases. Additionally, this type of system produces a highly concentrated chemical surge when water flow is resumed after being shut off for a period of time, since the lack of flow allows the chemical solution to become saturated. Finally, variation in the water flow rate will not correspondingly alter the dissolving rate of the chemical, producing incorrect concentration amounts in the outflow.
Attempts have been made to develop a mechanism which addresses the problems encountered in correctly metering and controlling the chemical introduction and concentration rates, but known systems are either overly complicated or do not fully solve all the problems set forth above. A complicated mechanism is described in U.S. Pat. No. 4,780,197 to Schuman, which discloses a flow-through chemical dispenser cartridge positioned within the internal core of a filter which requires one or more operational valves to perform effectively. A more simplified approach is shown in U.S. Pat. No. 4,347,224 to Beckert et al. This patent discloses a flow housing which contains an internally mounted chemical cartridge. A small amount of the water flow is diverted into the bottom of the chemical cartridge and the chemical solution is drawn through a small aperture in the top of the cartridge by the pressure differential created by the flow of the bulk of the water passing through the housing. This apparatus provides a simple approach to solving the problems encountered in standard solid chemical systems, but the mechanism is just a variation of the standard system where a portion of the water stream is passed through the solid chemical before being returned to the main flow stream. The distinction in Beckert et al. is that the cartridge containing the solid chemical is mounted internal to a large housing through which all the water flows. The sizing of the cartridge is such to create an annular passage down to the bottom of the chemical cartridge, where the water flows through a plurality of liquid inlet holes, past the chemical and out the liquid outlet hole. In effect, the annular passage is just a substitute for a small bypass conduit as found in many old systems, and the problems associated with variations in concentration and surging would still be present.
These problems have been addressed in various embodiments in my previous U.S. Pat. Nos. 5,580,448, 6,267,886, 6,280,617 and 6,855,252, the disclosures of which are incorporated herein by reference. However, a drawback inherent in these patents is that the chemical dispenser units are designed to be retained within the standard housings, bowls or bells used in combination with the standard inline base members. As such, the chemical dispenser units are limited in size, and replacement of the units once the chemical has been depleted requires multiple steps.
It is an object of this invention to provide a chemical dispenser device or assembly which provides a steady state concentration of dissolved chemical, which introduces the chemical solution into the main water stream in amounts directed related to water flow rate or volume to maintain precise percentages of chemical solution, which does not produce excessive chemical concentration during periods of no water flow, and which does not introduce excessive amounts of dissolved chemical when water flow is resumed, and wherein the chemical dispenser device is structured such that the amount of the solid chemical is not limited by the size of the standard housing, and further wherein removal and replacement of the chemical dispenser unit is quickly and easily accomplished, and further wherein in certain embodiments the volume of solid chemical and the dispensing rate can be changed by replacing certain components of the assembly, and further wherein in certain embodiments the connection mechanism for joining the chemical dispenser unit to the inline base member is a keyed, bayonet-type connection rather than a universal connection mechanism.